A clinical rating scale for progressive supranuclear palsy

We devised a Progressive Supranuclear Palsy (PSP) Rating Scale comprising 28 items in six categories: daily activities (by history), behaviour, bulbar, ocular motor, limb motor and gait/midline. Scores range from 0 to 100, each item graded 0-2 (six items) or 0-4 (22 items). Inter-rater reliability is good, with intra-class correlation coefficient for the overall scale of 0.86 (95% Cl 0.65-0.98). A single examiner applied the PSPRS at every visit for 162 patients. Mean rate of progression was 11.3 (11.0) points per year. Neither onset age nor gender correlated well with rate of progression. Median actuarially corrected survival was 73 years. The PSPRS score was a good independent predictor of subsequent survival (P < 0.0001). For example, for patients with scores from 40 to 49, 3-year survival was 41.9% (95% Cl 31.0-56.6) but 4-year survival was only 179% (95% Cl 10.2-31.5). For those patients, likelihood or retaining some gait function was 51.7% (40.0-66.9) at I year but only 6.5% (1.8-23.5) at 3 years. We conclude that the PSPRS is a practical measure that is sensitive to disease progression and could be useful as a dependent variable in observational or interventional trials and as an indicator of prognosis in clinical practice.